Manufacturing technique of self-punch and self-clinch component assembly

ABSTRACT

A METHOD OF FABRICATING A PART OR ASSEMBLY FROM SHEET MATERIAL BY SECURING ELEMENTS TO THE SHEET STOCK, ALIGNING A PARTING TOOL WITH RESPECT TO THE SECURED ELEMENTS AND THEREAFTER BLANKING OR OTHERWISE SEPARATING THE DESIRED CONFIGURATION FROM THE BALANCE OF THE SHEET MATERIAL WHEREBY THE PROFILE OF THE SHEET STOCK BASE PORTION OF THE ASSEMBLY IS NOT DISTURBED BY A SUBSEQUENT ATTACHMENT OF ANY ELEMENTS.

June 29, 1971 KLAUS ETAL 3,588,990

MANUFACTURING TECHNIQUE OF SELF-PUNCH AND SELF-CLINCH COMPONENT ASSEMBLY Filed Jan. 16, 1969 2 Sheets-Sheet 1 M VM TMS GEORGE F. KLAUS 19). ERIC H. PERSSON Af/M/VU June 29, 1971 KLAUS ETAL 3588,99

MANUFACTURING TECHNIQUE OF SELF-PUNCH AND SELF-CLINCH COMPONENT ASSEMBLY Filed Jan. 16, 1969 2 She-etsfiheet 2 United States Patent O U.S. Cl. 29-407 Claims ABSTRACT OF THE DISCLOSURE A method of fabricating a part or assembly from sheet material by securing elements to the sheet stock, aligning a parting tool with respect to the secured elements and thereafter blanking or otherwise separating the desired configuration from the balance of the sheet material whereby the profile of the sheet stock base portion of the assembly is not disturbed by a subsequent attachment of any elements.

BACKGROUND OF THE INVENTION This invention pertains to fabrication of assemblies and more particularly to assemblies which have one or more elements secured to a sheet material portion.

It is usually desirable and often vital to maintain both the dimensions between elements secured to a common sheet stock part and the configuration of the sheet stock portion of the assembly in the final fabricated condition. Many forms of fabrication cause distortion of one or both of the parts being secured as a result of elevated temperatures or mechanical deformation occurring during the process. Where such dimensional change occurs the cost to straighten or restore the completed assembly to the correct dimensions is often greater than that to fabricate the assembly. Further such rework, can cause undersirable alterations in the physical characteristics of the component materials.

SUMMARY OF THE INVENTION The present invention pertains to a method for fabricating assemblies wherein one or a series of elements are secured to a sheet stock portion. Rather than forming the individual parts and assemblying them one to another, the elements of the assembly to be secured to a sheet stock part are secured to a piece of unfabricated sheet stock and thereafter the desired form of the sheet material is pierced from the remainder of the stock. By locating the position of multiple elements to be secured to the sheet material with respect to those previously secured, accurate spacing can be maintained between such elements and through locating the parting tool with respect to such assembled elements the desired sheet material configuration is obtained during the severance of such part from the surrounding material. Accordingly the dimensional integrity of the final assembly is retained.

By this method of asembly not only can a distortion free base member be generated which is not subject to subsequent distortion, as would occur when an assembly member is attached to a previously blanked part, but it is also possible to secure a member close to the periphery of the ultimate configuration.

A further advantage is realized in the preparation and maintenance of drawings related to an assembly produced by this method, since normal practice requires only part drawings of the secured elements and an assembly drawing thereby eliminating the need for preparation and maintenance of a separate part drawing of the blanked sheet stock base member.

ice

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic isometric view of element of a die set oriented with respect to a strip of sheet stock in the form of a progressive die. FIG. 2 is a vertical longitudinal view partly broken away and partly in section showing a die set in closed position including the operative die elements of FIG. 1. FIG. 3 is an elevation, partly in section of the stud securing anvil of the third operating station. FIG. 4 is an elevation of the punch of operating station five shown partially in section.

DETAILED DESCRIPTION The method is illustrated in the schematic isometric view of FIG. 1 and in FIG. 2 in a vertical, longitudinal section of a die set in the closed position including the operating die elements of FIG. 1 in the environment of a progressive die. The die is utilized to fabricate an assembly having a plurality of elements attached to a sheet stock base member. In the illustrated embdiment an eleven station die including six operating stations is used with each operating station separated from the next adjoining operating station by an idle station to permit adequate space for die component mounting while affording economic use for die component mounting while affording economic use of the sheet stock material.

A strip 10 of sheet stock is indexed serially past the successive operating stations by an incrementing drive means (not shown) to permit simultaneous performance of operations on the strip at each of the operating stations during each stroke of the die. The progressive die as mounted in a press includes a stationary lower die block assembly 12 and series of operating elements which perform various shearing, punching and alignment functions mounted on an upper piercer or punch plate 13 for unitary reciprocating motion during each storke of the press. Stripper plate 15 has a common mode of operation wherein reciprocation occurs with a shorter stroke during each press cycle as a result of a lost motion connection with the punch plate 13. FIG. 1 schematically illustrates the operating die portions in a raised position prior to indexing of the strip stock while FIG. 2 shows the die set at the fully closed position of the press stroke.

At the first operating station a sleeve member 18, which forms a portion of the final assembly, is received about a positioning cylindrical end portion 20 of a mandrel punch 21 which also provides a pressure surface 22. To assure retention of sleeve 18 in concentric relation about cylindrical portion 20, a magnet carried by mandrel punch 21, the adhesive qualities of a film of grease on sleeve 18 or other commonly accepted methods may be utilized. Sleeve 18 is aligned with a cooperating shear edge 23 at the upper margin of the lower die opening 24 to afford connection to the sheet stock by a self-punching and self-clinching action during the downward stroke of mandrel punch 21.

At the second operating station pilot punch 26 enters the base of the sleeve element 27 twice indexed from the first operating station to align the strip 10 of sheet material before attachment of a successive sleeve element at the first operating station to assure establishment of the proper interval between operating stations.

At operating station three, the sleeve is again engaged by a pilot punch 29 while an anvil element 3!) guides a stud 33, retained in an axial recess 32 (FIG. 3), into secured engagement with the strip of material. Here the stud is positioned with respect to the previously attached sleeve and aligned with the shear edge of an opening in lower die block 35 to effect a self-punching and self-clinching connection. The stud may be retained by anvil 30 by any common method such as magnetically or temporary adhesion induced by a grease film applied to the stud.

At the fourth operating station a punch 38, also seen in FIG. 4, has a projecting pilot mandrel 39' which enters the base of the sleeve at this station and a cylindrical recess 40 which closely surrounds the stud to precisely align the shear edge 42 with respect to the assembled elements prior to the initiation of shearing cooperation between punch and the shear edge of the underlying die opening. Journaled within the lower die assembly is a blank restoring member 45 which has an enlarged lower portion 46 with an upper radial surface 47 which is normally urged against the lower surface 48 of the lower die element 35 by the biasing force of the compressed elastomeric cylinder 50 to normally present the upper surface of member 45 coplanar with the upper surface of die element 35. During the downward stroke of punch 38 the member 45 yields against the biasing force of elastomeric cylinder 50, but as the punch is withdrawn during its upward stroke member 45 restores the blanked portion of the strip to its former position.

The fifth operating station is provided to permit the fabricated assembly to be removed from the remainder of the sheet stock material by punch element 53. At this station the completed assembly 55 can be received by a conveyer (not shown) to effect automatic removal from the fabricating area. The sixth and final operating station includes a shear block 57 which, with die element 35, presents a pair of cooperating shear edges to cut the waste material which remains to a suitable reduced size for convenient disposal.

By securing the sleeve and thereafter the stud to the sheet stock the relative center distances can be accurately maintained. By attaching the secured elements of the assembly to the sheet stock prior to blanking, the sheet material base portion permits the base element to be formed accurately without a subsequent part attachment causing distortion. It is often important and at times vital that the contour of the base member be maintained with precision. Maintenance of a specific desired profile is necessary, for example, in the case of a cam formed of sheet stock to which is secured the bearing sleeve which affords adequate journal bearing surface for rotation.

Additionally, it is often possible only with great difficulty to attach an assembly member closely adjoining the periphery of a blanked sheet stock element. An element having this configuration is frequently ruined or severely distorted by such a fabrication sequence whereas by blanking the assembly from the sheet stock as the final 4 fabricating operation permits location of an assembly element closely adjoining the periphery without difiiculty.

What is claimed is:

1. A method of fabricating an assembly including a sheet material part comprising:

securing an element to a piece of sheet stock,

locating a tool relative to said sheet stock by alignment with said element; and

separating a portion of said sheet stock, to which said element is attached, from the balance thereof to generate a desired configuration of sheet material from said sheet stock.

2. The method of claim 1 wherein said element is secured to said sheet stock by a single operation and said sheet stock configuration is separated from the balance of sheet material by a blanking die and a cooperating punch element, said punch element including an element confining alignment surface.

3. The method of claim 1 wherein said element is secured to said sheet stock material and said sheet stock configuration is separated from the remaining sheet stock material by the operation of punch and cooperating die elements on a single machine.

4. The method of claim 1 wherein said separating is accomplished by a punch and further comprising supporting said sheet stock over a die adapted to cooperate with said punch and aligning said punch with said die.

5. The method of claim 4 wherein a series of similar assemblies are produced from sheet material comprising securing of said element to said sheet material at a first station, aligning said element at a second station, securing a succeeding element to said sheet stock at said first station as said element is aligned at said second station, positioning said sheet stock at a third station in overlying relation to said die and there separating said assembly from the balance of said stock.

References Cited UNITED STATES PATENTS 3,072,003 1/1963 Sirugue 83-213 3,233,485 2/1966 Creamer 837l 3,307,244 3/1967 De Shong 29-429X THOMAS H. EAGER, Primary Examiner US. Cl. X.R. 

